Paraffin scraper



Aug. 10, 1943.

L L l r Patented Aug. 10, 1943 PARAFFIN SCRAPEB.

Benjamin J. Festervan and Nathan F. Henler g son, Monroe City, Tex.

Application June 11, 1940, Serial No. 339,857

4 Claims.

The present invention is directed to a device for removing paraiiln from oil well tubing, and

for preventing` the accumulation of parailn therein.

, In our cci-pending application, Ser. No.'235,7`95,2

led Oct.`

19, 1938, now Patent No. 2,225,413,

granted December 17, 1940, and entitled varaffin Scrapers, we disclosed a device for userfm oil well 'tubing which is adapted topper-'ate on the go-devil principle. Iny the operation f lsaid cle.

vice, which is propelled'upwardly from a point intermediate the ends of the tubing to the top by the flow of oil, it is necessary to stop the ow of oil in order to permit the device to drop back to its starting point.

The principal object of the present invention is the provision of a paraffin scraper of the same general nature as that described in our aforesaid application which is capable of automatic and continuous operation without the necessity of stopping the now of oil in the tubing.

Further objects and advantages of our invention will appear from the accompanying drawing in which Figure 1 isa iront elevation of a device according to the present invention in place in an oil well tubing with the latter broken away to reveal the interior thereof;

Figure 2 is a vertical section through .the device of the present invention; and

Figure 3 is a detail View of one of the cutters.

Referring to the drawing in detail, and par' ticularly to Figure l, numeral l designates a borehole which, it will be understood, is normally cased and numeral 2 designates an oil producing tubing, known as an oil string, arranged Within:

said borehole connecting the producing formation with the surface. Fixed in tubing 2 at a point intermediate its ends, said point being selected below that at which paran begins to deposit, is a stop 3,' which is perforated to permit the passage of oil. This stop is shown in the most elementary manner for the sake of simplicity, and it is to be understood that in the practice of the present invention it is preferred to use the stop described yand claimed in our copending application, Ser. No, 236,862, filed Oct. 25, 1938, now Patent No. 2,213,580, granted Septomber 3, i940, and entitled a Stop for oil well casing and tubing, y

' The naraiiin scraper of the present invention is designated by numeral 4 and consists of a cylinder provided externally with longitudinally spaced discs 5, each of which is provided with helically arranged grooves 6. These discs are of also provided with circumferentially spacedlona size such that .there is a clearance of only about nl; of an inch, .or less, between `their periphery and the inner surface of the tubing. The spiral grooves serve the purpose of providing a passage -for upowing oil, which, in its passage, not only 'lifts the device, but by Virtue ofthe spiral grooves causes .the device as a whole to rotate whereby the teeth formed by the grooves act as a cutting means for removing accumulated paraffin. In this improved embodiment each of the discs is gitudinally extending. teeth 1,. which ,are so bevelled as to present a cutting edge in the direction of. rotationof the .discs to which they are attached.

By'reference to Figure 3, which represents the upper disc 5, it will be seen that the disc is adapted to rot-ate to the right and that the teeth 'I are s0 bevelled as to form a cutting edge 8 facing the direction of rotation. The teeth 'I on the upper discextend upwardly and the teeth 1 on the lower disc extend downwardly, so that on the upwward travel of the scraper the upper teeth I will be adapted to cut away any extra thick deposits of parafn, and likewise on the downward travel of the scraper, the lower teeth 'I will be adapted .to serve the same purpose.

The lower disc 5 is held in place -by a cap 9 which has circumferentially spaced ports I0, and which has in its lower end va central opening II adapted to receive a -rod I2 on the lower end of which is a semicircular plate I3 which serves the4 purpose of bringing the scraper to rest against the stop 3 without closing the opening nsaid Stop. Y

The upper end of rod I2 is provided with a conicle head I4 which is adapted to seat against a bevelled edge I5 on the lower end of cylinder 4. The inner end of rod I2 has arecess I6 in which is a string II working against a. piston I8 vto which is attached a rod I9 extending the length of the scraper and protruding beyond the upper end thereof through a hole 20 in a cap 2| which serves to hold the upper cutting disc 5 in place. The hole 2u is large enough to admit a iishing tool which may be of .the character described in our cri-pending application Ser. No. 235,794, led Oct. 19, 1938, now Patent No. 2,243,- 419, granted May 27, 1941, and entitled Fishing tool, this fishing tool being adapted to coact with the angular portion 22 of the upper end of the cap. The rod I9 isprovided with a spacer 23 which rides in the cap 2|-.

The upper end of tubing 2 vhas a plate or other n up and down an oil well the rod Il strikes when the scraper rises to the 811111.66.

In the use of the device in the present invention, it is placed in the tubing.` falls by gravity to the stop I, the force of its impact with the stop being sufllcient to force valve Il on to its seat I5. The oil coming up through the stnp 3 then is forced to pass aroundthe cutting discs 5 4and in so doing forces the scraper upwardly while simultaneously rotating it. When the scraper reaches the top of the tubing 2, the upper end of rodA I9 `strikes against the plate 2| and forces the valve Il of! its seat.- The springv l1 serves to absorb the shock when the rod I9 hits the A plate 2l. With the valve Il opened oil is able to flow through the cylinder I whereby the scraper is free to drop in the tubing bygravity.

It will be apparent that changes may be made in the device of the present invention without departing from the scope thereof. Such changes are contemplated within the scope of the dependent claims. in which it is intended to claim f the present invention asbrcadly as the prior art permits.

We claim: f

l. A paramn scraper adapted to move` freely tubing comprising a hollow open-ended cylinder, circumferential cutters mounted on such cylinder, helical passages insaid cutters. a valve adapted to stop the flow of oil through said cylinder whereby oil is forced throughsaid helical passages, means carried by the cylinder for closing said valve when the cylinder reaches its lowermost position in the tubing, and for opening said valve when the cylinder reaches its uppermost position in the tubing.

2. A paramn scraper adapted to move freely up and down sn oil well tubing between stops arranged in said tubing comprising. a hollow, open ended cylinder, circumferential cutters mounted on said cylinder, a valve adapted to stop the flow ofoil through said cylinder, and projections on either side of said valve protruding beyond either end of said cylinder, whereby when the cylinder reaches the lowermost stop the valve is closed, and when the cylinder reaches the uppermost stop the valve is opened.

3. A paraffin scraper according to claim 2 in which the circumferential cutters have an outside diameter only slightly smaller than the inside diameter of the tubing and are provided with helical grooves spaced circumferentially on their outer surfaces, whereby movement of fluid through said grooves causes rotation of the cutters.

`4. A paraffin scraper adapted to move freely up 'and down an oil well tubing between stops arranged in said tubing comprising a hollow open-ended cylinder, circumferential cutters mounted on said cylinder, a valve seat in said cylinder, a valve adapted to be seated on said seat, a rod extending from said valve to a point below4 the lower end of said cylinder and adapted .to strike the lowermost of said stops in the downward travel of said cylinder to move said valve into closed position, a rod extending from said valve upwardly to a point above the upper end of said cylinder and adapted to strike the uppermost of said stops on the upward travel of said cylinder to thereby open said valve, and a resilient connection between said latter rod and said valve.

" BENJAMIN J. FESTERVAN.

NATHAN F. HENDERSON. 

